How about making the ‘dp_packet’ member the first member and adding a comment
that this should be first?
Jarno
> On Oct 10, 2016, at 8:42 AM, Bodireddy, Bhanuprakash
> <bhanuprakash.bodire...@intel.com> wrote:
>
> Hello jarno,
>
> Thanks for the feedback, while reordering the members of dpif_upcall, I had
> to deviate from standards due to below reason.
> The dp_packet member has mbuf as first member that starts at new cache line
> creating hole of size 60 bytes between dpif_upcall_type and dp_packet as
> pointed below.
>
> struct dpif_upcall {
> enum dpif_upcall_type type;
>
>
> --> 60 bytes hole
>
> /* --- cacheline 1 boundary (64 bytes) --- */
> struct dp_packet {
> struct rte_mbuf {
> /* typedef MARKER */ void * cacheline0[0]; /*
> 64 0 */
>
> }
> struct nlattr * key;
>
> .
> .
> }
>
> I tried to pack this hole by moving other members in to this space.
>
> Regards,
> Bhanu Prakash.
>
>> -----Original Message-----
>> From: Jarno Rajahalme [mailto:ja...@ovn.org]
>> Sent: Friday, October 7, 2016 10:11 PM
>> To: Bodireddy, Bhanuprakash <bhanuprakash.bodire...@intel.com>
>> Cc: dev@openvswitch.org
>> Subject: Re: [ovs-dev] [PATCH 09/12] dpif: Reorder elements in dpif_upcall
>> structure.
>>
>> CodingStyle.md instructs to group struct members into related groups. Also,
>> changing the relative order of pointers should not make any difference. Could
>> you achieve the same by reordering just the members above the
>> ‘DPIF_UC_ACTION only.’ comment?
>>
>> Jarno
>>
>>> On Oct 7, 2016, at 9:17 AM, Bhanuprakash Bodireddy
>> <bhanuprakash.bodire...@intel.com> wrote:
>>>
>>> By reordering the data elements in dpif_upcall structure, pad bytes
>>> can be reduced and also a cache line.
>>>
>>> Before: structure size:768, holes:1, sum padbytes:60, cachelines:12
>>> After: structure size:656, holes:1, sum padbytes:4, cachelines:11
>>>
>>> Signed-off-by: Bhanuprakash Bodireddy
>>> <bhanuprakash.bodire...@intel.com>
>>> Signed-off-by: Antonio Fischetti <antonio.fische...@intel.com>
>>> ---
>>> lib/dpif.h | 17 +++++++++--------
>>> 1 file changed, 9 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/lib/dpif.h b/lib/dpif.h
>>> index a7c5097..4a4bb3d 100644
>>> --- a/lib/dpif.h
>>> +++ b/lib/dpif.h
>>> @@ -779,17 +779,18 @@ const char *dpif_upcall_type_to_string(enum
>>> dpif_upcall_type); struct dpif_upcall {
>>> /* All types. */
>>> enum dpif_upcall_type type;
>>> - struct dp_packet packet; /* Packet data. */
>>> - struct nlattr *key; /* Flow key. */
>>> - size_t key_len; /* Length of 'key' in bytes. */
>>> - ovs_u128 ufid; /* Unique flow identifier for 'key'. */
>>> - struct nlattr *mru; /* Maximum receive unit. */
>>> - struct nlattr *cutlen; /* Number of bytes shrink from the end. */
>>>
>>> /* DPIF_UC_ACTION only. */
>>> - struct nlattr *userdata; /* Argument to
>> OVS_ACTION_ATTR_USERSPACE. */
>>> - struct nlattr *out_tun_key; /* Output tunnel key. */
>>> struct nlattr *actions; /* Argument to OVS_ACTION_ATTR_USERSPACE.
>> */
>>> + struct nlattr *out_tun_key; /* Output tunnel key. */
>>> + struct nlattr *userdata; /* Argument to
>> OVS_ACTION_ATTR_USERSPACE. */
>>> +
>>> + struct nlattr *cutlen; /* Number of bytes shrink from the end. */
>>> + struct nlattr *mru; /* Maximum receive unit. */
>>> + ovs_u128 ufid; /* Unique flow identifier for 'key'. */
>>> + struct dp_packet packet; /* Packet data. */
>>> + struct nlattr *key; /* Flow key. */
>>> + size_t key_len; /* Length of 'key' in bytes. */
>>> };
>>>
>>> /* A callback to notify higher layer of dpif about to be purged, so
>>> that
>>> --
>>> 2.4.11
>>>
>>> _______________________________________________
>>> dev mailing list
>>> dev@openvswitch.org
>>> http://openvswitch.org/mailman/listinfo/dev
>
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